I can confirm this is still happening. We have had this issue about a year ago and decided to switch hosting provider, where we never had issues.
Now we are back on a datacenter in Dallas, and the same issue arises yet again. (We have made no changes in the server setup whatsoever during the migration)
In the past few months we were doing well in terms of player population. Servers filled up instantly. Now with the new machine (dedicated server) we are struggling to get even 6 to 8 players on, even though our name is established already. A lot of regulars are reporting not being able to find the server (25000 or ? ping) or not being able to join it at all ("Connecting Failed").
Some players on the other hand seem to be able to find and join fine. In either case, it killed our server within a few days, with little to no-one playing on it anymore. We ran into a dead end last year when researching this problem, and are yet again very frustrated with this...